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Randomized Controlled Trial
. 2009 Jun;50(6):2560-6.
doi: 10.1167/iovs.08-2693. Epub 2009 Jan 17.

Effectiveness of placebo therapy for maintaining masking in a clinical trial of vergence/accommodative therapy

Marjean Kulp  1 , G Lynn Mitchell, Eric Borsting, Mitchell Scheiman, Susan Cotter, Michael Rouse, Susanna Tamkins, Brian G Mohney, Andrew Toole, Kathleen Reuter; Convergence Insufficiency Treatment Trial Study Group
Affiliations
Randomized Controlled Trial

Effectiveness of placebo therapy for maintaining masking in a clinical trial of vergence/accommodative therapy

Marjean Kulp et al. Invest Ophthalmol Vis Sci. 2009 Jun.

Abstract

Purpose: To evaluate the effectiveness of the Convergence Insufficiency Treatment Trial (CITT) placebo therapy program in maintaining masking of patients randomized to the office-based treatment arms, determine whether demographic variables affect masking, and determine whether perception of assigned treatment group was associated with treatment outcome or adherence to treatment.

Methods: Patients (n = 221, ages, 9-17 years) were randomized to one of four treatment groups, two of which were office-based and masked to treatment (n = 114). The placebo therapy program was designed to appear to be real vergence/accommodative therapy, without stimulating vergence, accommodation, or fine saccades (beyond levels of daily visual activities). After treatment, patients in the office-based groups were asked whether they thought they had received real or placebo therapy and how confident they were in their answers.

Results: Ninety-three percent of patients assigned to real therapy and 85% assigned to placebo therapy thought they were in the real therapy group (P = 0.17). No significant differences were found between the two groups in adherence to the therapy (P >or= 0.22 for all comparisons). The percentage of patients who thought they were assigned to real therapy did not differ by age, sex, race, or ethnicity (P > 0.30 for all comparisons). No association was found between patients' perception of group assignment and symptoms or signs at outcome (P >or= 0.38 for all comparisons).

Conclusions: The CITT placebo therapy program was effective in maintaining patient masking in this study and therefore may have potential for use in future clinical trials using vergence/accommodative therapy. Masking was not affected by demographic variables. Perception of group assignment was not related to symptoms or signs at outcome (ClinicalTrials.gov number, NCT00338611).

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Figures

Figure 1
Figure 1
Flow of office-based patients in the CITT. Patients assigned to the two home-based treatments are not included (n = 107). †One missed visit.
Figure 2
Figure 2
Level of confidence, by actual therapy, of patients who thought they had received real therapy.
See this image and copyright information in PMC

References

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